The present invention relates to an apparatus for composing a plurality of sets of color separations of, for example, yellow (Y), magenta (M), cyan (C), and black (BK), by adhering them on to desired positions of transparent base sheets for every separated color.
In a conventional photomechanical process, there has been work called "composing" in which a plurality of sets of original films, color separated by a color separation device such as a color scanner or the like, are adhered onto the base sheets of respective elemental colors by relatively positioning. This work is performed by positioning a plurality of sets of original films, in general one set consists of four sheets of original films such as Y, M, C and BK, and adhering them respectively on relatively identical positions of four base sheets for four elemental colors. Conventionally, this work has been carried out by hand with low efficiency, while requiring high proficiency.
An apparatus for automatically carrying out the composing work is disclosed in U.S. Pat. No. 4,599,122. This automatic apparatus comprises a frame, an original film storage case, a transporting device for transporting the original films, a registering light table, a base sheet storage case and a case for receiving the composed base sheets. In addition, four independent devices are provided on the frame. The first is a film picking-up device for picking up one sheet of original film from the base sheet storage case, the second is an original film moving device which provides a camera for optically detecting the register marks of the picked up original film, the third is an original film transporting and adhering device for transporting the original film attached thereto in X, Y and .theta. directions, and the last is a base sheet transporting device for transporting the base sheet. The above-described apparatus performs the "composing work" according to the following process.
Register marks are previously set at each of the corresponding positions of one set of the original films. This process is performed by recording the desired register marks together with the picture images, for example, in color separation work by a color scanner. According to a desired printing layout, each sheet of the first color (for example, yellow, hereinafter refer to as the "first color") among the plurality of sets of color separated original films is adhered to a base sheet by hand. By setting the base sheet on an adequate digitizer, the positions of the register marks of the first color original film are read out and stored in a memory. The first color original films adhered to the base sheet are removed from the base sheet and the original films and the base sheet are stored in their respective storage cases. Then, the apparatus is driven in sequence and the original film pick-up device picks up the original films from the original film storage case and sets them on the original film transporting device where positioning of the original film is roughly performed. Next, the original film moving device carries the original films to the registering light table where the positions of the register marks are read with the optical detecting camera. Simultaneously, the base sheet transporting device carries the base sheet from the base sheet storage case to the composing table and sets it thereon. Then, the original film transporting and adhering device holds the original film on the registering light table and the original film is aligned, according to the position data read out by the digitizer and the data optically detected by the detecting camera, to a desired position on the base sheet and set thereon. The original film is adhered thereon with an adhesive tape or the like. The afore-described process is repeated as necessary for the first color, and when all of the original films of the first color are composed on the base sheet, the base sheet is fed to the base sheet receiving case by the base sheet transporting device. The same process is repeated for the original films of the second and the following colors.
The above-described conventional composing apparatus can be carried out automatically, however, there are the following disadvantages. If the original films of the first color are not removed from the base sheet on which they were composed according to a desired layout by hand, and the base sheet is used in the following process with respect to original films of the second and the following colors, and if they are composed on the base sheet according to the data of composing position of the first color original films read out by the digitizer, position errors may sometime occur between the original films of the first color and those of the second color. The reason lies in that position reading of the register marks of the original films by the digitizer is carried out by aligning the cursor line of the digitizer by human eyes so that positioning errors on the order of a few hundred microns occur. Accordingly, this results in registering inaccuracy.
In the above described conventional apparatus, once the original films read out by the digitizer are all removed from the base sheet and the original films of all the separation colors are composed on the base sheets by the same process the inaccuracy is eliminated. Thus, positioning errors are prevented. According to this process, the position of all the original films of a plurality of separated colors can be aligned appropriately. However, in the first step gaps occur between the position of the original films composed by hand according to a desired layout and the actual positions to which the original films are adhered. In addition, in this process the original films are adhered to the desired position of the base sheet after elaborate alignment and the original films are adhered by the composing apparatus. As described, there is only a low working efficiency for this apparatus. Further, in the afore-mentioned apparatus, it is indispensably necessary to drive four kinds of transporting or moving devices along one axis or a plurality of axes, so that a complicated and large-scaled mechanism is required, and adjustment is necessary to keep the high accuracy.